/*
 * Date Format 1.2.3
 * (c) 2007-2009 Steven Levithan <stevenlevithan.com>
 * MIT license
 *
 * Includes enhancements by Scott Trenda <scott.trenda.net>
 * and Kris Kowal <cixar.com/~kris.kowal/>
 *
 * Accepts a date, a mask, or a date and a mask.
 * Returns a formatted version of the given date.
 * The date defaults to the current date/time.
 * The mask defaults to dateFormat.masks.default.
 */

(function(global) {
    'use strict';

    var dateFormat = (function() {
        var token = /d{1,4}|m{1,4}|yy(?:yy)?|([HhMsTt])\1?|[LloSZWN]|'[^']*'|'[^']*'/g;
        var timezone = /\b(?:[PMCEA][SDP]T|(?:Pacific|Mountain|Central|Eastern|Atlantic) (?:Standard|Daylight|Prevailing) Time|(?:GMT|UTC)(?:[-+]\d{4})?)\b/g;
        var timezoneClip = /[^-+\dA-Z]/g;

        // Regexes and supporting functions are cached through closure
        return function (date, mask, utc, gmt) {

            // You can't provide utc if you skip other args (use the 'UTC:' mask prefix)
            if (arguments.length === 1 && kindOf(date) === 'string' && !/\d/.test(date)) {
                mask = date;
                date = undefined;
            }

            date = date || new Date;

            if(!(date instanceof Date)) {
                date = new Date(date);
            }

            if (isNaN(date)) {
                throw TypeError('Invalid date');
            }

            mask = String(dateFormat.masks[mask] || mask || dateFormat.masks['default']);

            // Allow setting the utc/gmt argument via the mask
            var maskSlice = mask.slice(0, 4);
            if (maskSlice === 'UTC:' || maskSlice === 'GMT:') {
                mask = mask.slice(4);
                utc = true;
                if (maskSlice === 'GMT:') {
                    gmt = true;
                }
            }

            var _ = utc ? 'getUTC' : 'get';
            var d = date[_ + 'Date']();
            var D = date[_ + 'Day']();
            var m = date[_ + 'Month']();
            var y = date[_ + 'FullYear']();
            var H = date[_ + 'Hours']();
            var M = date[_ + 'Minutes']();
            var s = date[_ + 'Seconds']();
            var L = date[_ + 'Milliseconds']();
            var o = utc ? 0 : date.getTimezoneOffset();
            var W = getWeek(date);
            var N = getDayOfWeek(date);
            var flags = {
                d:    d,
                dd:   pad(d),
                ddd:  dateFormat.i18n.dayNames[D],
                dddd: dateFormat.i18n.dayNames[D + 7],
                m:    m + 1,
                mm:   pad(m + 1),
                mmm:  dateFormat.i18n.monthNames[m],
                mmmm: dateFormat.i18n.monthNames[m + 12],
                yy:   String(y).slice(2),
                yyyy: y,
                h:    H % 12 || 12,
                hh:   pad(H % 12 || 12),
                H:    H,
                HH:   pad(H),
                M:    M,
                MM:   pad(M),
                s:    s,
                ss:   pad(s),
                l:    pad(L, 3),
                L:    pad(Math.round(L / 10)),
                t:    H < 12 ? 'a'  : 'p',
                tt:   H < 12 ? 'am' : 'pm',
                T:    H < 12 ? 'A'  : 'P',
                TT:   H < 12 ? 'AM' : 'PM',
                Z:    gmt ? 'GMT' : utc ? 'UTC' : (String(date).match(timezone) || ['']).pop().replace(timezoneClip, ''),
                o:    (o > 0 ? '-' : '+') + pad(Math.floor(Math.abs(o) / 60) * 100 + Math.abs(o) % 60, 4),
                S:    ['th', 'st', 'nd', 'rd'][d % 10 > 3 ? 0 : (d % 100 - d % 10 != 10) * d % 10],
                W:    W,
                N:    N
            };

            return mask.replace(token, function (match) {
                if (match in flags) {
                    return flags[match];
                }
                return match.slice(1, match.length - 1);
            });
        };
    })();

    dateFormat.masks = {
        'default':               'ddd mmm dd yyyy HH:MM:ss',
        'shortDate':             'm/d/yy',
        'mediumDate':            'mmm d, yyyy',
        'longDate':              'mmmm d, yyyy',
        'fullDate':              'dddd, mmmm d, yyyy',
        'shortTime':             'h:MM TT',
        'mediumTime':            'h:MM:ss TT',
        'longTime':              'h:MM:ss TT Z',
        'isoDate':               'yyyy-mm-dd',
        'isoTime':               'HH:MM:ss',
        'isoDateTime':           'yyyy-mm-dd\'T\'HH:MM:sso',
        'isoUtcDateTime':        'UTC:yyyy-mm-dd\'T\'HH:MM:ss\'Z\'',
        'expiresHeaderFormat':   'ddd, dd mmm yyyy HH:MM:ss Z'
    };

    // Internationalization strings
    dateFormat.i18n = {
        dayNames: [
            'Sun', 'Mon', 'Tue', 'Wed', 'Thu', 'Fri', 'Sat',
            'Sunday', 'Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday'
        ],
        monthNames: [
            'Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec',
            'January', 'February', 'March', 'April', 'May', 'June', 'July', 'August', 'September', 'October', 'November', 'December'
        ]
    };

    function pad(val, len) {
        val = String(val);
        len = len || 2;
        while (val.length < len) {
            val = '0' + val;
        }
        return val;
    }

    /**
     * Get the ISO 8601 week number
     * Based on comments from
     * http://techblog.procurios.nl/k/n618/news/view/33796/14863/Calculate-ISO-8601-week-and-year-in-javascript.html
     *
     * @param  {Object} `date`
     * @return {Number}
     */
    function getWeek(date) {
        // Remove time components of date
        var targetThursday = new Date(date.getFullYear(), date.getMonth(), date.getDate());

        // Change date to Thursday same week
        targetThursday.setDate(targetThursday.getDate() - ((targetThursday.getDay() + 6) % 7) + 3);

        // Take January 4th as it is always in week 1 (see ISO 8601)
        var firstThursday = new Date(targetThursday.getFullYear(), 0, 4);

        // Change date to Thursday same week
        firstThursday.setDate(firstThursday.getDate() - ((firstThursday.getDay() + 6) % 7) + 3);

        // Check if daylight-saving-time-switch occured and correct for it
        var ds = targetThursday.getTimezoneOffset() - firstThursday.getTimezoneOffset();
        targetThursday.setHours(targetThursday.getHours() - ds);

        // Number of weeks between target Thursday and first Thursday
        var weekDiff = (targetThursday - firstThursday) / (86400000*7);
        return 1 + Math.floor(weekDiff);
    }

    /**
     * Get ISO-8601 numeric representation of the day of the week
     * 1 (for Monday) through 7 (for Sunday)
     *
     * @param  {Object} `date`
     * @return {Number}
     */
    function getDayOfWeek(date) {
        var dow = date.getDay();
        if(dow === 0) {
            dow = 7;
        }
        return dow;
    }

    /**
     * kind-of shortcut
     * @param  {*} val
     * @return {String}
     */
    function kindOf(val) {
        if (val === null) {
            return 'null';
        }

        if (val === undefined) {
            return 'undefined';
        }

        if (typeof val !== 'object') {
            return typeof val;
        }

        if (Array.isArray(val)) {
            return 'array';
        }

        return {}.toString.call(val)
            .slice(8, -1).toLowerCase();
    };



    if (typeof define === 'function' && define.amd) {
        define(function () {
            return dateFormat;
        });
    } else if (typeof exports === 'object') {
        module.exports = dateFormat;
    } else {
        global.dateFormat = dateFormat;
    }
})(this);